Carcinoma recti. The predictive value of diagnostic biopsies for histologic grading.

The differentiation of 39 diagnostic biopsies, as determined by histologic grading, and that of the corresponding 39 rectal carcinomas were compared. About 60 percent of grade I tumors were diagnosed by grade I biopsies, while about 90 percent of grade II and only about 40 percent of grade III tumors were diagnosed by grade II and grade III biopsies, respectively. The results indicate caution when biopsy grading is used as a guidance to therapy, especially of poorly differentiated tumors.